EP2044869B1 - Cyclical heat exchanger for preparing drinks, in particular water heating unit for coffee makers - Google Patents

Abstract

The cold water is guided through an inlet (5) located at the lower end of a pipe-shaped (4) instant water heater (1) with a central resistance heating element (2). The heating element (2) has an outer thread (3) serving as a guide for the water, which is released from an outlet (6) at the upper end of the pipe (4). A water receptacle (16) is formed between the lower end of the heater (2) and the bottom of the outer pipe (4) facilitating the transmission of ultrasonic waves created in a device (9) positioned below in order to prevent the accumulation of lime scales.

Description

The invention relates to a continuous heat exchanger for the preparation of beverages, in particular water instantaneous water heater for coffee preparation machines according to the preamble of claim 1.

The document DE 102 45 824 B describes a continuous heat exchanger.

In this context, continuous heat exchangers are to be understood as meaning thermal units which heat or cool a liquid fluid flowing through them, in particular heat water in order to prepare a drink or make steam with it, the heat of the fluid not being released by another fluid or needs to be included, but eg can be generated by a fixed electrical resistance heater or by electrical induction. In accordance with the invention highlighted by flow heaters for the production of brewing water or steam in coffee making machines such continuous heat exchangers.

Various continuous flow heat exchange systems are known for the heating or cooling of liquid fluids in the continuous process. Disadvantage of these systems is that they calcify, for example when heating water, depending on the degree of hardness, more or less quickly or narrow, for example, when cooling fluids by deposits of impurities their flow paths.

In particular, fall in the heating of water in a water heater as a continuous heat exchanger in the water bound calcium ions and store preferably at the hottest points of the heat source, with which they come into thermal contact when flowing through flow paths, as a hard surface. The deposits or calcifications are not only a disturbing insulating layer for heat transfer, but also narrow the flow paths. This constriction can lead to the complete closure of the continuous heat exchanger, and thus to the failure or even destruction of the continuous heat exchanger and thus to loss of use of the entire device. For this reason, the flow paths of the continuous heat exchangers have relatively large cross sections in order to ensure the longest possible trouble-free operation. However, large cross sections require a relatively large heat output of the entire heater system, since, due to the large cross section, per unit of time larger amounts of water must be heated, which in turn exert a large cooling effect on the heating system.

These deposits or calcifications, as long as there is still a river, can be completely or partially removed with the aid of mostly acidic descaling agents. In many devices that use continuous heat exchangers, sensors for indicating the degree of calcification are therefore provided, which give an indication of the need for descaling.

Apart from a removal of a completed calcification methods are known to avoid from the outset a calcification. For this purpose, ion exchangers are switched between the continuous heat exchanger and the fresh water inlet, which exchange the calcium ions for sodium ions. These ion exchange materials are mostly encapsulated in exchangeable cartridges.

The above-mentioned descaling or calcification prevention methods all require the use of chemical descaling agents to be supplied in an additional operation or the use of exchangeable ion exchange cartridges. At high water hardness levels, the ion exchangers are consumed very quickly. In the case of small flow path cross-sections, the narrowing caused by the calcification occurs very quickly, as a result of which only small amounts of the chemical decalcifying agent can attack the calcifications, which makes descaling considerably more difficult. For these reasons, therefore, heat exchangers with low heat capacity and small flow path cross sections could not be used so far.

Furthermore, it is known that calcifications can also be eliminated or even prevented by sonication of the liquid-filled calcified or contaminated spaces with ultrasound. The operating principle of decalcification and cleaning is the cavitation resulting from the ultrasonic field, i. the formation and dissolution of cavities in liquid due to pressure fluctuations. The ultrasound field irradiated into the liquid generates overpressure and underpressure in these waves. If such a vacuum wave encounters an obstacle, e.g. Limescale, formed on small air bubbles larger cavities filled with steam. When a subsequent high pressure wave impinges on the cavity, the static pressure in the cavity increases as a result of its compression above the saturation vapor pressure. As a result, the vapor bubbles condense abruptly with the speed of sound. These cyclically occurring and vanishing cavities act on the calcium deposits or other deposits and destroy or solve them mechanically.

The present invention is based on the object, a continuous heat exchanger for the preparation of drinks, in particular a water water heater for coffee preparation machines to provide the aforementioned type, the small flow path cross-sections for the liquid to be heated or cooled, in particular water to be heated, and thus may have low heat output and nevertheless long-term reliable operation with high efficiency. With such a water heater in coffee preparation machines, a quick operational readiness after switching on the device and a quick change from coffee brewing to steam preparation and vice versa can be achieved.

This object is achieved with a continuous heat exchanger having the features of claim 1.

Through the use of ultrasonic transducers whose ultrasonic frequency and sound power can be optimized depending on the geometry of the room to be sounded or the structure to be sonicated, continuous heat exchangers, in particular instantaneous water heaters, with small flow path cross sections and low heat capacity can be realized.

For this purpose, depending on the construction of the continuous heat exchanger, the ultrasonic vibrators may be expediently integrated in this or flanged on the outside thereof.

Advantageous variants and further developments of the continuous heat exchanger will become apparent from the subclaims 2 to 14.

According to the invention, the continuous heat exchanger is a tubular continuous heat exchanger.

According to the invention, the ultrasonic oscillator is integrated in one end face of the continuous heat exchanger.

In the latter case, the ultrasonic vibrator can be integrated in a particularly uncomplicated and effective manner according to the invention in an end face of the outer sleeve of the tubular continuous heat exchanger.

Continuous tubular heat exchangers according to the invention can alternatively be heated, each with an electrical resistance heater or heated with induction heat.

In the case of heating the continuous heat exchanger with induction heat, an induction heater is expediently arranged on the outer sleeve of ferromagnetic material.

In the tubular continuous heat exchangers, each with an electrical resistance heater, the flow path or the flow paths can be cut directly in the form of a single or multiple thread in an electrical resistance insert, which is used in the center of the continuous heat exchanger, see claim 2, wherein an outer boundary of the flow path is formed by the seated on the heating rod outer sleeve.

In a variant of the thread-shaped flow path but also be formed according to claim 3 inside in the outer sleeve.

In a further variant of the flow path formation according to claim 4, a thread-shaped flow path may be formed externally in an intermediate sleeve, which is arranged between the outer sleeve and the electrical resistance insert.

A plurality of parallel thread or helical flow paths of the continuous heat exchanger constitute multi-spindle flow paths according to claim 6.

The flow paths of the beverage or water to be heated or cooled can, insofar as they are not curved by design, in particular be helical, be designed as linear flow paths according to claim 7. The flow paths need not be consistently linear.

In particular, in the case where the continuous flow heat exchanger according to claim 8 is designed as a water heater having a heater in heat-conducting connection with the flow path or flow paths for the heating water, it may have zones of different heating capacities along the flow path, wherein a first of the zones, which is located closest to entry of the water in the flow path, has a higher heat output than others of the zones. Thus, the degree of calcification along the flow path can be set to be higher in the first of the zones that is closest to the entrance of the water into the flow path than in other of the zones that are further downstream of the entrance are adjacent, which is especially true for differentiated flow path cross-sections adjacent to the zones may be advantageous, as will be explained below.

If the continuous flow heat exchanger or water water heater, as preferred, is part of a coffee maker, according to claim 9 may also expediently a second zone, namely the one which is located closest to an exit of the water from the flow path, a higher heat output than another of the zones of the heater adjacent to a flow path section upstream of the exit. In this case, switching from coffee preparation to steam operation of the water flow heater avoids so-called supply water from the water flow heater exits before a steam outlet.

The above-mentioned differentiated design of the flow path cross-section of the flow path of the water to be heated or drink can be achieved according to claim 10, characterized in that the depth of the flow path decreases in the flow direction to the outlet of the flow path.

Alternatively or additionally, however, it can also be provided that the pitch of the thread-shaped flow path decreases in the flow direction from the entry of the beverage or water into the flow path to the outlet, which can also result in a decreasing flow path cross section.

In both cases results from the relatively large flow path cross section at the beginning of the flow path in conjunction with the above-mentioned relatively high heat output in the adjacent zone of the heater, a relatively strong calcification, whereby the calcification of the following Section of the flow channel is kept relatively low. In the section of larger cross-section, the comparatively soon occurring calcification may be less disturbing, because this section can be better decalcified, also because the larger amount of water present in it leads to a better coupling of the ultrasound into the water.

For the same purpose of the good coupling of the ultrasound may be formed according to claim 12 in the continuous heat exchanger between the ultrasonic oscillator and the flow path, a fluid collecting space.

For the application according to the invention ultrasonic vibrators can be used with different principles of action, in particular according to claim 13 piezoelectric vibrator or according to claim 14 magnetoresistive oscillator.

Embodiments of the invention are illustrated in the drawing with three figures and described below, from which further advantageous details may result.

Figur 1

eine erste Ausführungsform eines Durchlaufwärmetauschers in einer Seitenansicht, teilweise geschnitten,

Figur 2

eine zweite Ausführungsform des Durchlaufwärmetauschers, ebenfalls in einer Seitenansicht, teilweise geschnitten, und

Figur 3

eine dritte Ausführungsform des Durchlaufwärmetauschers in einer Seitenansicht.

It shows:

FIG. 1

A first embodiment of a continuous heat exchanger in a side view, partially in section,

FIG. 2

a second embodiment of the continuous heat exchanger, also in a side view, partially cut, and

FIG. 3

a third embodiment of the continuous heat exchanger in a side view.

Identical parts are provided in the figures with corresponding reference numerals.

The first embodiment of the continuous heat exchanger after FIG. 1 shows a tubular continuous heat exchanger 1 with internal electrical resistance heating insert 2 and integrated ultrasonic transducer 9. A flow path 3 for the water to be heated is cut in the form of a thread directly on the heating element 2. The outer boundary of the flow path is formed by an outer shell 4 firmly seated on the heating insert 2. The supply of a liquid fluid, in particular cold water, is a fluid inlet nozzle 5 and the derivative of the heated fluid or water, a fluid outlet nozzle 6, which are in fluid communication with the beginning or end of the flow path 3. Between a lower side of the resistance heating insert 2 and a bottom of the outer sleeve 4 adjoining the ultrasonic oscillator 9, a fluid collecting space 16 is formed in the latter, which is likewise connected to the water inlet connection 5 via a section of the flow path 3. The fluid or water in the fluid collection chamber 1 6 ensures effective transmission of the ultrasonic power from the ultrasonic vibrator 9 to the fluid or water in the flow channel 3 during descaling operation.

The second embodiment of the continuous heat exchanger according to FIG. 2 is also tubular and also includes an internal electrical resistance insert 2 'and an integrated ultrasonic transducer. 9

It is in the embodiments according to the Figures 1 - 3 to the same piezoelectric design of the ultrasonic vibrator with a provided with high frequency terminals 14, 15 piezoelectric disk 10 between a coupling cone 11 at the bottom of the outer sleeve 4 and 4 'and a Gegenlastscheibe 12, wherein these elements of the ultrasonic vibrator 9 are held together by a screw 13 which generates a mechanical bias.

In the second embodiment, flow paths are formed by a respective space, which releases a coil spring 7 applied to the heating insert 2 'to the resistance heating insert 2 on the one hand or the outer sleeve 4' on the other hand. The flow paths run in the helical spring 7 helically.

When electrical resistance heaters or resistance heating inserts are used, the throughflow heater parts forming the flow paths may consist of various heat-resistant and highly heat-conducting, preferably metallic materials.

A third embodiment of the water heater according to FIG. 3 with integrated ultrasonic vibrator differs from the first embodiment and the second embodiment in that the heating of the water heater is realized by an induction heater 8 on the outer sleeve 4b of ferromagnetic material.

The electrical resistance insert 2 or 2 'in the Figures 1 and 2 and the induction heater 8 in FIG. 3 , each representing a heater, may have zones of different heating powers over their length or height, eg according to different pitch of the helical induction heater 8, advantageously the zones adjacent to the fluid inlet nozzle, eg 5, and adjacent to the fluid outlet nozzle, eg 6, with increased heating power are dimensioned.

The temperature of the heater or its zones is expediently monitored and regulated with temperature sensors (not shown).

Instead of in the Figures 1 and 2 shown resistance insert 2 or 2 'as an internal electrical resistance heater can be arranged externally in another embodiment of the continuous heat exchanger, a resistance heater.

In the Figures 1 and 2 are the flow path 3 and the coil spring 7, which limits at least one flow path, shown uniformly over the length thereof. However, it may be advantageous to make the depth of the thread, which forms the flow path, for example 3, or the pitch of the helical spring 7 in the region of the fluid inlet nozzle, for example 5, much greater than in the further course of the passage section or the flow path. Optionally, the thread depth or the slope, starting from the fluid inlet nozzle, for example, 5, continuously decrease. The greater thread depth or pitch, in conjunction with increased heating power provided in the adjacent zone of the heater as shown above, results in locally increased calcium precipitation, which requires later sonication due to the larger cross section of this flow path section and the flow path section of smaller cross section less quickly calcified or polluted. Another zone of increased heating power, namely at the fluid outlet nozzle, for example, 6, however, has the purpose to avoid when switching hot water production for coffee preparation to steam production so-called supply water.

In the following the function of the different embodiments of the continuous heat exchanger is described with ultrasonic vibrator:

Referring to the FIGS. 1 to 3 In particular, cold water for hot water production or steam generation under line or pump pressure via the fluid inlet nozzle 5 enters the tubular flow heater 1 and is conveyed through the flow heater 1 in the flow path 3 or the flow paths. During the passage, the water is heated in the tubular water heater 1, depending on the embodiment by means of the electrical resistance heating element 2 or by means of the induction heater 8 and exits through the fluid outlet nozzle 6.

A sonication of the continuous heat exchanger 1 and the fluid contained therein by means of integrated in the continuous heat exchanger or to the continuous heat exchanger ultrasonic vibrator 9 can both automatically during each preparation cycle of a drink or after a predetermined number of preparation cycles at intervals, or in a separate run, or during a rinsing process take place before or after a preparation cycle.

LIST OF REFERENCE NUMBERS

1

tubular continuous heat exchanger

2, 2 '

electrical resistance heating insert

3

flow path

4, 4a, 4b

outer sleeve

5

Fluid inlet nozzle

6

Fluid outlet port

7

coil spring

8th

induction heating

9

ultrasonic vibrator

10

piezodisc

11

coupling cone

12

Against load sheave

13

Screw (mechanical preload)

14

RF connector

15

RF connector

16

Fluid collection space

17

Fluid collection space

Claims (14)

1. Cyclical heat exchanger for preparing drinks, in particular water heating unit for coffee makers having at least one flow path (3) of the drink or water to be heated or cooled,
   wherein an ultrasonic generator (9, 21) is in ultrasonically conductive connection with the flow path,
   characterized in
   that the cyclical heat exchanger is designed as a tubular cyclical heat exchanger (1),
   that the tubular cyclical heat exchanger (1) includes a substantially cylindrical outer shell (4, 4a, 4b),
   that in the outer shell (4, 4a, 4b) an electric resistance insert (2, 2' is arranged or
   on the outer shell (4b) of ferromagnetic material an induction heating (8) is arranged and
   that the ultrasonic generator (9) is integrated in one front side of the outer shell (4).
2. Cyclical heat exchanger according to claim 1, characterized in
   that on the electric resistance heating insert (2), the flow path (3) of the drink or water to be heated is formed out in the shape of a thread
   and that an outer limitation of the flow path is defined by the outer shell (4) provided on the heating insert.
3. Cyclical heat exchanger according to claim 1,
   characterized in
   that a thread-shaped flow path (3) is formed out at the inside of the outer shell (4).
4. Cyclical heat exchanger according to claim 1,
   characterized in
   that between the outer shell and the electric resistance insert an intermediate shell is arranged and
   that a thread-shaped flow path is formed out at the outside of the intermediate shell.
5. Cyclical heat exchanger according to claim 1
   characterized in
   that in the outer shell (4), an electric resistance insert (2') is arranged on which a helical spring (7) is applied which together with the outer shell forms an outer flow path and with the resistance insert (2') forms an inner flow path.
6. Cyclical heat exchanger according to one of claims 1 to 5,
   characterized by
   multi-spindle flow paths.
7. Cyclical heat exchanger according to claim 1,
   characterized by
   linear flow paths.
8. Cyclical heat exchanger according to one of the foregoing claims,
   characterized in
   that a heater which is in heat conductive connection with the at least one flow path (3) includes, along sections of the flow path (3), zones of different heating capacity and
   that a first one of the zones disposed in the flow path nearest to the entry of the water has a higher heating capacity than another one of the zones.
9. Cyclical heat exchanger according to claim 8,
   characterized in
   that also a second one of the zones disposed in the flow path nearest to the exit of the water has a higher heating capacity than another one of the zones.
10. Cyclical heat exchanger according to claims 2 to 5,
    characterized in
    that the depth of the flow path (3) decreases in the flow direction of the drink or water in the flow path (3) towards its exit.
11. Cyclical heat exchanger according to claims 2 to 4,
    characterized in
    that the pitch of the thread-shaped flow path (3) decreases in the flow direction from the entry of the drink or the water into the flow path towards its exit
12. Cyclical heat exchanger according to one of the foregoing claims,
    characterized in
    that in the cyclical heat exchanger, between the ultrasonic generator (9) and the flow path (3), a fluid collecting room (16, 17) is provided.
13. Cyclical heat exchanger according to one of the foregoing claims,
    characterized by a piezo vibrator as the ultrasonic generator (9).
14. Cyclic heat exchanger according to one of claims 1 to 12,
    characterized by
    a magnetostrictive transducer as the ultrasonic generator (9).

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